Analog or digital information may be communicated to a remote receiver using a variety of communication theory techniques. A typical transmission system includes a transmitter, a communication channel, and a receiver. The transmitter coverts the analog or digital information into a form that is suitable for transmission over the communication channel. The receiver recreates the original information from the transmitted signal. The communication channel may be any transmission medium such as wire, optical fiber, or merely free space in which the signals are transmitted as an electromagnetic wave (e.g., radio and television signals).
In a typical wireless communication system, a data signal that includes the information is modulated with a carrier signal and transmitted into free space with an antenna. The receiving system has an antenna and receiver that are tuned to the carrier frequency. The receiving system demodulates the received signal and extracts the data signal.
As the transmission signal propagates through the communication channel, noise and other non-ideal effects such as signal interference may degrade the transmission signal. The transmitter and receiver are carefully designed such that the data signal can be extracted from the transmission signal despite the introduction of noise and other non-ideal effects.